water beetles of china

JAcil & Jl (cds.): Water Beetles of China Vol. Ill 21 - 3 6 Wien, April 2003

Key to adults of Chinese water beetle families

(Coleoptera)

M.A. JÄCH & M. BALKE

Abstract

A key to Chinese water beetle families (True Water Beetles and Phytophilous Water Beetles), basedon adults, is presented. All distinguishing characters mentioned in the key are illustrated. A check listof families of True Water Beetles, Phytophilous Water Beetles, and False Water Beetles occurring inChina is included. Habitus paintings representing all Chinese families of True Water Beetles, Phyto-philous Water Beetles, and some families of Shore Beetles are provided.

Key words: Coleoptera, True Water Beetles, Phytophilous Water Beetles, Facultative Water Beetles,Shore Beetles, False Water Beetles, key, China.

Introduction

An annotated check list of aquatic and riparian beetle families of the world, including briefdescriptions of their preferred habitats, was published by JÄCH (1998). A total of 24 families ofTrue Water Beetles, Phytophilous Water Beetles and False Water Beetles presently is known tooccur in China (see check list below). Of these 24 families, four recently were recorded for thefirst time: Aspidytidae (see BALKE et al. 2003), Epimetopidac (see Jl & JÄCH 1998), Spercheidae(see JIA 1996), and Torridincolidae (see JÄCH 1998). As for Shore Beetles and Facultative WaterBeetles, most of the families listed by JÄCH (1998) can be encountered in China. However, theoccurrence of Parasitic Water Beetles has not been confirmed so far.

The key to families presented herein includes True Water Beetles and Phytophilous WaterBeetles known from China. Facultative Water Beetles, False Water Beetles, and Shore Beetlesare not included in the key. However, habitus illustrations of some representatives of the mostcommon families of Chinese Shore Beetles (Carabidae, Georissidae, Heteroceridae,Limnichidae, Sphacriusidae, Staphylinidae) are provided to enable their easy recognition (seeFigs. 50 - 55).

A world-wide key for the identification of water beetle families has not been published so far. Asmall selection of regional keys is listed in the references (AMANN et al. 1994, HuiJBREGTS 1992,DUDGEON 1999, KLAUSNITZER 1996, MCCAFFERTY 1981, NILSSON 1996, RICHOUX 1982, WATTS

1998, WHITE & BRIGHAM 1996, WHITE et al. 1984).

Check list of families of True Water Beetles, Phytophilous Water Beetles,and False Water Beetles occurring in China

A) True Water Beetles (adults usually partly or totally submerged, larvae aquatic or riparian):

Myxophaga: Hydroscaphidae (Fig. 18), Torridincolidae (Fig. 19)

Adephaga: Amphizoidae (Fig. 22), Aspidytidae (Fig. 23), Dytiscidae (Figs. 26 - 29), Gy-rinidac (Figs. 20, 21), Haliplidae (Fig. 30), Mygrobiidae (Fig. 25), Notcridac (Fig. 24)

© Wiener Coleopterologenverein, Zool.-Bot. Ges. Österreich, Austria; download unter www.biologiezentrum.at

22 JÄCH & BALKE: Key to Chinese water beetle families

Polyphaga: Dryopidae (Figs. 41 - 43), Elmidae (Figs. 44 - 46), Epimetopidae (Fig. 40),Helophoridae (Fig. 39), Hydraenidae (Figs. 31 - 33), Hydrochidae (Fig. 34), Hydrophil-idae (Figs. 35 - 37), Spercheidae (Fig. 38)

B) Phytophilous Water Beetles (adults and larvae always closely associated with water plants):

Polyphaga: Chrysomelidae (Figs. 47,48), Curculionidae (Fig. 49)

C) False Water Beetles (adults terrestrial, larvae aquatic):

Polyphaga: Eulichadidae, Lampyridae, Psephenidae, Ptilodactylidae, Scirtidae

Key to Chinese water beetle families (adults only)

The key to families presented herein includes True Water Beetles and Phytophilous WaterBeetles known from China. Besides morphological distinguishing characters this key alsoincludes data about habitat preference, abundance and regional distribution in China. Thecharacters and size ranges given for each family (or genus) are referring exclusively to theChinese fauna.

All morphological characters used for identification in this key are easy to recognize, even forinexperienced students and ecologists. Almost all morphological characters are figured. Accuratehabitus paintings in colour are provided for each family; these paintings may enable quickrecognition of at least some of the more characteristic representatives.

The beginner may find it very useful to know, that the most common water beetles collected instagnant water are Dytiscidae and Hydrophilidae. Larger specimens usually always belong to oneof these two families. For inexperienced students the distinction between Hydrophilidae andDytiscidae is normally the very first hurdle on their way to becoming a specialist. A short glanceat the ventral surface, which is always densely pubescent in Hydrophilidae and glabrous inDytiscidae, is usually sufficient to ensure successful determination. In contrast to samples takenfrom stagnant water, the beetle fauna of running waters often is dominated by Elmidae.

Important notice: Very often, limnological samples include Shore Beetles (see Figs. 50 - 55) oreven strictly terrestrial species. Although aquatic and riparian beetles usually exhibitmorphological adaptations (e.g. oar-like legs, swimming hairs, stream-lined body shape,burrowing legs) these are often very cryptic and not readily detectable for students. A generaland unambiguous distinction between aquatic, riparian and fully terrestrial beetles often isimpossible in preserved specimens.

1 Head prolonged in front of eyes to form distinct rostrum (snout), which is always much longerthan wide (Fig. 1). Antenna inserted on rostrum, geniculate between first and second segment(Fig. 1). Length: ca. 1.5 - 7.5 mm. Habitus (Fig. 49). Stagnant water, wide-spread, notcommonly collected CurculionidaeHead anteriorly not prolonged into distinct rostrum. Antenna not geniculate between first andsecond segment 2

2 Elytron with outer apical angle produced into a long spine (Fig. 47). Length: ca. 6 - 7 mm.Habitus (Fig. 47). Stagnant water, very rare (Gansu) Chrysomelidae (genus Macroplca)Elytron without spine on outer apical angle; if elytron produced apically (e.g. hydrophilidgenus Berosus or some elmid genera) - then general habitus totally different and antennamuch shorter 3

3 Third tarsal segment of all legs bilobed (Figs. 2, 48). Length: ca. 3 - 11 mm. Habitus (Fig. 48).Stagnant water, wide-spread, not common Chrysomelidae (excl. genus Macroplea)Third tarsal segment never bilobed in hind legs 4


in JÄCH & Jl (eels.): W a t e r Beet les o f Ch ina , Vol . I l l , 2003 23

4 Middle and hind legs strongly modified (fiat, oar-like), much shorter than forelegs (Figs. 20,21). Head with two pairs of well-developed eyes, one on dorsal side and one on ventral side(Fig. 3). Length: ca. 4 - 2 7 mm. Habitus (Figs. 20, 21). Stagnant and running water, wide-spread, quite common Gyrinidae

All legs approximately equally long. Head usually with one pair of eyes (very rarely, e.g. inthe hydrophilid genus Amphiops with two pairs) 5

5 Hind femur and basal abdominal ventritcs concealed by conspicuous "coxal plates" (Fig. 14).Length: ca. 2.0 - 4.6 mm. Habitus (Fig. 30). Stagnant or slowly flowing water, wide-spread,not uncommon Haliplidae

Hind femur and basal abdominal ventritcs never concealed 6

6 Antenna straight, club-shaped, with continuous outline (Fig. 19), very short, not reachinganterior margin of head (Fig. 19). Length: ca. 1.5 mm. Habitus (Fig. 19). Running water,hygropetric habitats, rare (Anhui, Fujian) Torridincolidae

Antenna variously shaped (see Figs. 7 - 10), long or short, always surpassing anterior marginof head (Figs. 18, 22 - 46) 7

7 Metacoxae forming very large plate, with conspicuous midcoxal area (Figs. 13, 15, 16):Dytiscoidea 8

Metacoxae distinctly smaller, never forming very large plate (Figs. 17) 12

8 Legs modified for swimming, usually with dense fringes of long swimming hairs (Figs. 13,15, 16, 24 - 29); tarsomeres of hind leg flattened (Figs. 13, 15, 16, 24 - 29) 9

Legs more or less unmodified (Figs. 22, 23), without dense fringes of long swimming hairs;tarsomeres of hind leg long and slender, cylindrical, not flattened 11

9 Metacoxal plate with anterior paramedian angle (Fig. 15). Body dorsally strongly convex,ventral surface almost flat. Posterior metacoxal process very large (Fig. 15). Suture betweenfirst two ventrites partly or completely obsolete (Fig. 15). Length: ca. 2 - 5 mm. Habitus (Fig.24). Mainly in stagnant water, wide-spread, not uncommon Noteridae

Metacoxal plate without anterior paramedian angle (Figs. 13, 16). Body dorsally and ventrallyconvex. Metacoxal process small (Figs. 13, 16). Suture between first two ventrites well-developed (Figs. 13, 16) 10

10 Lateral parts of metaventrite characteristically arcuately acuminate, resembling falcon wings(Fig. 13). Metaventrite without transverse suture (Fig. 13). Length: 1 - 50 mm. Habitus (Figs.26 - 29). Very common in stagnant water, less common in running water, wide-spread.. DytiscidaeLateral parts of metaventrite not arcuately acuminate (Fig. 16) and thus not resembling falconwings. Metaventrite with transverse suture (Fig. 16). Length: ca. 10 mm. Habitus (Fig. 25).Stagnant water, very rare (Jiangxi), might be extinct in China Hygrobiidae

11 Body outline discontinuous, with pronoto-elytral angle (Fig. 22). Surface structure rugulose.Length: ca. 10 - 14 mm. Habitus (Fig. 22). Mountain streams, rare (Sichuan, Jilin)... Amphizoidae

Body outline more or less continuous, without pronoto-elytral angle (Fig. 23). Surface structu-re smooth. Length: ca. 5 mm. Habitus (Fig. 23). Wet cliffs, very rare (Shaanxi) Aspidytidae

12 Pronotum with pronounced anteromedian projection forming shelf above head (Fig. 40). Firstventrite very short and inconspicuous, abdomen therefore apparently with four visible sternites(ventrites). Length: ca. 3 mm. Habitus (Fig. 40). Margins of streams, very rare (Hainan)

EpimetopidaePronotum without pronounced anteromedian projection. Abdomen with four to seven visiblesternites (ventrites) 13

13 Labrum strongly deflected, not seen from above (Fig. 38). Anterior margin of clypcusdistinctly emarginate with anterior corners upturned (Fig. 38). Length: ca. 6 mm. Habitus (Fig.38). Stagnant water, very rare (Heilongjiang) Spercheidae

Labrum usually visible from above, rarely strongly deflected. Anterior margin of clypcus notdistinctly emarginate 14



14 General appearance as in Fig. 34. Middle of pronotum with three shallow impressions (Fig.34). Length: ca. 2 - 4 mm. Habitus (Fig. 34). Stagnant water, wide-spread, not very common...

Hydrochidac

General appearance not as in Fig. 34 15

15 General appearance as in Fig. 39. Pronotum with five longitudinal grooves (Fig. 39). Length:ca. 2 - 6 mm. Habitus (Fig. 39). Stagnant water, common in N China, rare or absent in SChina HclophoridacGeneral appearance not as in Fig. 39 16

16 Elytra distinctly abbreviated and truncate, thus posterior abdominal segments exposed andvisible from dorsal view (Figs. 18, 31). Terminal abdominal segment triangular (Figs. 18, 31).... 17

Elytra not abbreviated and truncate as in Figs. 18, 31. Terminal abdominal segment usuallynot visible from dorsal view, rarely long and triangular 18

17 Maxillary palpi very short, about half as long as distance between eyes (Fig. 18). Antennastraight (Fig. 18); antennal insertion exposed, visible from above (Fig. 18). Length: < 2 mm.Habitus (Fig. 18). Gravelly margins of running water, very rarely collected (SE China)

Hydroscaphidac

Maxillary palpi rather long, about as long as distance between eyes (Fig. 31). Antenna ofhydrophiloid type (first segment usually long and curved, club pubescent, Fig. 4); antennalinsertion dorsally obtected by lateral extension of frons and clypeus, therefore not visible fromdorsal view (Fig. 6). Length: ca. 0.9 - 2.5 mm. Habitus (Fig. 31). Stagnant and running water,wide-spread, not uncommon Hydraenidae (genus Limnebius)

18 Antenna typically hydrophiloid (first segment usually long and curved, club pubescent, Figs. 4- 6); antennal insertion dorsally obtected by lateral extension of head, therefore not visiblefrom dorsal view (Fig. 6) 19

Antenna of varying appearance (see Figs. 8 - 12, 41 - 46), if vaguely resembling hydrophiloidtype (e.g. Elmidae: Larainae, Fig. 8) then entirely pubescent; antennal insertion exposed,visible from dorsal view (Figs. 12, 41 - 46) 20

19 Pubescent antennal club with five segments (Fig. 4). Length: ca. 1 - 3 mm. Habitus (Figs. 32,33). Stagnant and running water, wide-spread, common

Hydraenidae (excl. genus Limnebius)

Pubescent antennal club with three segments (Fig. 5). Length: ca. 2 - 4 0 mm. Habitus (Fig. 35- 37). Very common in stagnant water, less common in running water, wide-spread

Hydrophilidac20 Antenna very short (Fig. 7); second segment (pedicel) greatly enlarged and strongly produced

to form distinct subtriangular plate (Figs. 7, 12, 41, 43). Frontoclypeal suture absent (Fig. 12).Length: 3 - 8 mm. Habitus (Figs. 41, 43). Quite common in running water, less common instagnant water, wide-spread Dryopidac (excl. genus Ceradryops)

Antenna short or long (Figs. 8-10, 42, 44 - 46), second segment (pedicel) never produced toform subtriangular plate. Frontoclypeal suture usually present (Fig. 11) 21

21 Eyes covered with numerous interfacetal setae (Fig. 42). Antenna short, 6-segmented;however, last four segments closely jointed and therefore antenna seemingly 3-segmented(Fig. 42). Frontoclypeal suture absent. Length: ca. 1.5 - 2.0 mm. Habitus (Figs. 42).Hygropetric habitats, very rare (Hong Kong) Dryopidac (genus Ceradryops)

Eyes naked, without interfacetal setae (Figs. 44 - 46). Antenna short or long, with 7 - 1 1segments (Figs. 8 - 10). Frontoclypeal suture usually present (Fig. 11). Length: ca. 1—6 mm.Habitus (Figs. 44 - 46). Very common in running water, wide-spread Elmidae

Acknowledgements

We thank D. Paramonov (Riga) and W. Zelenka (Vienna) for the habitus illustrations(Paramonov: Figs. 26 - 29, 35 - 37, Zelenka: remaining Figs.). We are very much obliged to J.Kodada (Bratislava), A. Komarek (Vienna), A.S. Konstantinov (Washington), P. Mazzoldi(Brescia), and I. Ribera (London) for valuable comments.


in JÄCII & Jl (cds.): Water Hectics of China, Vol. III. 2003 25

scapus

intermediate

pedicellus

11

10 12

Figs. 1 - 12: 1) Head of Curculionidac, dorsal view; 2) habitus of leaf beetle; arrow points at bilobedtarsomcre of hind leg; 3) head of Gyrinidac, lateral view; 4) antenna of Hydraenidae; 5) antenna ofHydrophilidae; 6) head of Hydrophilidac, dorsolatcral view, arrow points at obtected antennal base;7) antenna of Dryopidac; 8-10) various types of antennae of Elmidae; 11) head of Elmidae, dorsal view,arrow points at free antennal base; 12) head of Dryopidae, dorsal view.



antenna maxillary palpus

'wings

metaventrite

metacoxa

metacoxalT^Tl process

ventrites

metaventrite

'wings

\ metaventrite

metacoxalplates

metaventrite

paramedian anglemetacoxa

Antenna maxillary palpus

transversesuture

metacoxa

midcoxal area

metaventrite

metacoxa

Figs. 13-17: Ventral side of 13) Dytiscidae, 14) Haliplidae, 15) Noteridae, 16) Hygrobiidae,17) Hydrophilidae


.lA( II K .11 ( o i l s . ) : W a t e r I k r t l c s o l ' C h i n a . V o l . I I I . 2 0 0 3 27

18

21

Figs. IX - 21: Habitus of IS) llyclroscapliitlac (//w/msccip/id), W) Torridincolidae (Stiioiüus)20) (iyrinidac (Mctngvrimis), 2 1) (iyrinidac (Porroiiiyncliiix).


28 JÄCll & BAI.KK: Key to Chinese water hectic families

Figs. 22 - 25: Habitus of 22) Amphizoidac (Amphizoa), 23) Aspidytidae (Aspidytes), 24) Notcridae(Canfhydrus), 25) Hygrobiidae (Hygrohia).


inJÄcil & JKccis.): Walcr Ikvlics ol'Cliina. Vol. 111,200.? 29

26

\\

V

' igs. 26 29: llahilu.s «.>( 2C>) Dydsc idac (Copc/atiis), 21) Dytisciciac (/fyc/rovatii.s), 28) Dyt isc idaclÜTtes), 29) Dytiscidac (Cyhistcr).


30 JÄCU & BALK.!:: Key to Chinese water beetle families

\

32

Figs. 30 33: Habitus of 30) Haliplidae {Pcltodytes), 31) Hydracnidae {l.imnchius), 32) Hydracnidae(Aitlacochthebius), 33) Hydracnidae (Ilyilracna).


i n J Ä C H & J l ( a l s . ) : W i i l c r B e e t l e s o l ' ( ' l i i n a . V o l . I l l , 2 0 0 3 31

f '•••

34

\

36

38

l;igs. 34 3N: Habitus oC34) I lydrocludac (Ilydroclm.s), 35) I lydropliilidac (Berosits), 36) llydrophilidac{l/i'locluiri's), 37) I Ivdmpliilidae (IIvilrophilus), 3S) Spcivhcidac (Spcrcheus).


32 JÄCH & BAI.KK: Key to Chinese water beetle families

41

Figs. 39 -42 : Habitus of 39) Hclophoridac (llelophoms), 40) Epimctopidac (Eumclopits), 41) Dryopidac(Stenomystax), 42) Dryopidae (CeraJryop.s).


i n . l u l l cV .11 ( c t l s ) : \ \ ; i k - i I k v l k - s o l C l n i i a . \ ' o l . I I I . 2 0 0 . 1 33

Figs. 43 - 46: Habitus o f 4 3 ) Dryopidac (Dryop.s), 44) I . lmidae (Dryopomorplws), 45) l ümidac(Ciispick'via), 46) l-'lmidac (Stciwlmis).


34 JÄcn & BALKH: Key to Chinese water beetle families

48

49 50

Figs. 47 - 50: Habitus of 47) Chrysomelidae (Macroplea), 48) Chrysomelidae (Prusocuris),4()) Curculionidae (Bagons), 50) Sphacriusidac (Sphacrius).


in JÄcil et Jl (eels.): Water Beetles of China, Vol. I l l , 2( 35

Figs. 5 1 55: I labitus ol"5 1) C'arabidac (l-'.laphnis), 52) Stapln linidac (Dianous), 53) Gcorissidac((Icorissus), 54) I Icteroivridae (Heteroccrn.s), 55) l.immehidac (liyrrhinus).



References

AMANN, E., BRANDSTETTER, CM. & KAPP, A. 1994: Käfer am Wasser (Gattungsschlüssel der (semi-)aquatischen Käfer Mitteleuropas). - Bürs: Erster Vorarlberger Coleopterologischer Verein, 38 pp.

BALKE, M., RIBERA, I. & BEUTEL, R.G. 2003: Aspidytidae: On the discovery of a new beetle family:detailed morphological analysis, description of a second species, and key to fossil and extantadephagan families (Coleoptera), pp. 53-66. - In Jäch, M.A. & Ji, L. (eds.): Water Beetles ofChina, Vol. III. - Wien: Zoologisch-Botanische Gesellschaft in Österreich and WienerColeopterologenverein, VI + 572 pp.

HuiJBREGTS, H. 1992: 6. Tabel tot de families van (semi)aquatische Coleoptera, pp. 58-60. - In Drost,M.B.P., Cuppen, H.P.P.J., Nieukerken, E.J. van & Schreijer, M. (eds.): De waterkevers vanNederland. - Utrecht: Uitgeverij K.N.N.V., 280 pp.

DUDGEON, D. 1999: Tropical Asian streams. Zoobenthos, ecology and conservation. - Hong Kong: HongKong University Press, xii + 830 pp.

JÄCH, M.A. 1998: Annotated check list of aquatic and riparian/littoral beetle families of the world(Coleoptera), pp. 25-42. - In Jäch, M.A. & Ji, L. (eds.): Water Beetles of China, Vol. 2. - Wien:Zoologisch-Botanische Gesellschaft in Österreich and Wiener Coleopterologenverein, 371 pp.(Internet: http://www.nhm-wien.ac.at/nhm/2Zoo/coleoptera/publications/chinaindex.html)

Ji, L. & JÄCH, M.A. 1998: Epimetopidae: Synopsis of the genus Enmetopus Balfour-Browne(Coleoptera), pp. 195-205. - In Jäch, M.A. & Ji, L. (eds.): Water Beetles of China, Vol. 1. - Wien:Zoologisch-Botanische Gesellschaft in Österreich and Wiener Coleopterologenverein, 371 pp.

JiA, F. 1996: The Hydrophiloid Beetles in China. - Guangzhou: Zhongshan University, unpublishedthesis, 252 pp.

KLAUSNITZER, B. 1996: Käfer im und am Wasser. - Magdeburg: Westarp Wissenschaften, andHeidelberg: Spektrum Akademischer Verlag (Die Neue Brehm-Bücherei; Bd. 567), 200 pp.

McCAFFERTY, W.P. 1981: Aquatic Entomology. - Boston: Science Books International, 448 pp.

NiLSSON, A.N. 1996: Coleoptera, Introduction. - In Nilsson, A.N. (ed.): Aquatic Insects of North Europe -A Taxonomic Handbook. - Stenstrup: Apollo Books, pp. 115-122.

RlCHOUX, P. 1982: Introduction pratique ä la systematique des organismes des eaux continentalesfrancaiscs. 2. Coleopteres aquatiques. - Bulletin mensuel de la Societe Linneenne de Lyon 51 (4,8, 9): 56 pp. (105-128, 257-272, 289-333).

WATTS, C. 1998: Preliminary guide to the identification of adult and larval Dytiscidae and adult aquaticHydrophilidac (Insecta: Coleoptera). - Identification guide (Cooperative Research Centre forFreshwater Ecology (Australia)) 19: 48 pp.

WHITE, D. & BRIGHAM, W.U. 1996: 20. Aquatic Coleoptera, pp. 399-473. - In Merritt, R.W. &Cummins, K.W. (eds.): An introduction to the aquatic insects of North America. - Dubuque:Kendall/Hunt, 862 pp.

WHITE, D., BRIGHAM, W.U. & DOYEN, J.T. 1984: 19. Aquatic Coleoptera, pp. 361-437. - In Merritt,R.W. & Cummins, K.W. (eds.): An introduction to the aquatic insects of North America. -Dubuque: Kendall/Hunt.

Dr. Manfred A. JÄCI1Naturhistorisches Museum, Burgring 7, A - 1014 Wien, Austria ([email protected])

Dr. Michael BALKliZoologische Staatssammlung München, Münchhausenstr. 21, D - 81247 München, Germany

Present address: The Natural History Museum, Department of Entomology, Cromwell Road, London SW7 5BD,UK ([email protected])


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